Accurate and efficient diagnostic techniques are an essential requirement of efforts to prevent and treat sexually transmitted diseases. Nucleic acid hybridization assays will be developed for this purpose using new technologies recently developed in our laboratory. These techniques include a chemical method for labeling probes with biotin and assay formats in which hybridization reactions take place in solution and in which assays can be performed in microtiter plates and the results can be measured spectrophotometrically. The format involves a reaction between DNA sequences and complementary DNA sequences. The probe, either DNA or RNA depending on the nucleic acid analyze to be detected, is labeled with biotin. Labeled hybrids are detected in an immunoreaction with a solid phase anti-biotin antibody and enzyme labeled monoclonal antibody specific for DNA-RNA hybrids. Monoclonal solution hybridization assays will be developed and standardized for the detection of Chlamydia trachomatis and human papillomaviruses. A prospective evaluation of the performance of these hybridization assays compared to other diagnostic systems for the detection of these microbes will be performed with urethral and cervical specimens from patients attending an STD clinic. To expand the diagnostic capabilities of hybridization assays, a genomic library from an LGV strain of C. trachomatis will be constructed and the library will be screened for genotype specific clones. Clinical isolates of C. trachomatis will be tested in hybridization assays using genotype probes in order to determine the correlation between genotype, classical serovar and biotype defined by clinical characteristics of the patient from whom the isolate was obtained. The successful development of practical techniques for detection of nucleic acids in clinical specimens may improve the care of patients with STDs and allow for greater understanding of the epidemiology and pathophysiology of these infections.